Photobiomodulation is a new field of medicine where generally low power light or low power laser radiation is applied to tissue with the idea of prompting a cellular response. Although the physical chemistry is not well understood, some theories and empirical data indicate that the light interacts with the cell mitochondria and stimulates the energy production of the cell. Once cells performing a certain function get energized a physiological response is observed. There are many tens of indications that have been the basis of photobiomodulation experimentation and clinical studies ranging from local aesthesia to dermatological disorders. Some of the areas that have been best studied are increase of blood flow, reduction in inflammation and wound healing. It is known that certain light applied to the skin will cause an increase in blood flow.
An ischemic stroke is caused by a blood clot in the brain limiting blood flow thereto and causing oxygen deprivation. Brain cells die in a stroke, therefore, immediate treatment is necessary to avoid or limit permanent brain damage.
Studies are under way to use lasers to stimulate blood flow to the brain during a stroke. These studies involve illuminating the scalp with a high power laser and shining light through the hair, skin, hair follicles, and skull into the brain.